1. Field
This disclosure relates generally to semiconductor processing, and more specifically, to a semiconductor package structure having under-die pads.
2. Related Art
Ball Grid Array (BGA) is a semiconductor packaging technology in which a semiconductor die is mounted on a top surface of a BGA package substrate and a plurality of solder balls is formed in a grid pattern on a bottom surface of the BGA package substrate. The BGA package can then be attached to a printed circuit board (PCB), in which the grid of solder balls of the BGA package forms electrical connections between the die and the PCB. However, the coefficient of thermal expansion (CTE) of the semiconductor die is typically low compared to the BGA package substrate and compared to the PCB. This results in a region of high stress at the solder balls which are located directly below the die, in particular at those solder balls which are located directly below the die edges. The die edges form the highest regions of stress due to the die being mechanically attached to the BGA package substrate by a die attach adhesive or underfill epoxy material. The BGA package substrate is thereby restrained by the die. The high stress region causes the BGA interconnects located within the region to mechanically fail before BGA interconnects outside of this region due to thermally induced stress.